[cwconfig] Add "pyramid" config type to MCOMPAT dict I don't know what this is for exactly, but the accept_mode method below queries this dict with the configuration type name. And if the latter is "pyramid", it crashes since there's no key in MCOMPAT dict. So add one with the same value as "all-in-one". This code is called during "upgrade" migration in particular.

[pyramid] Avoid shutting down the repository at exit if it's already shutting down For install `cubicweb-ctl pyramid` command will explicitly call `repo.shutdown()` so the atexit hook is redundant. Prevent the latter to be executed when the repository is already shutting down (otherwise one gets an assertion error).

[server/test] Extract a "ldapsource" function in unittest_ldapsource.py We will add more use of this pattern in forthcoming changesets, so avoid repetition.

[server] Move "system" source initialization into its own method

[entities] Make CWSource's dictconfig method clearer

[entities] Move CWSource update_config method as a function in 3.15 migration script This script is the only caller of this method. In the code of the function, drop "skip_unknown" argument and continue accordingly upon OptionError.

[server/test] Turn "pull" method of LDAPFeedTestBase into a staticmethod Because it does not use reference to "self" (which should be "cls" for classmethod).